[IgG subclasses: placental transfer in the full-term neonate and their evolution during the first 3 months of life].

The authors studied the placental transfer of IgG subclasses in 43 newborns (NB) and their mothers. All the observations included low-risk pregnancies and full-term deliveries. The values expressed in arithmetric mean +/- standard deviation (means +/- SD), and referred in mg %, showed the following results: maternal Ig Gtotal 1,183 +/- 237 versus (vs.) NBG 1,179 +/- 187; maternal Ig G1 792 +/- 230 vs. NB 822 +/- 124; maternal Ig G2 138 +/- 77 vs. NB 209 +/- 70; maternal Ig G3 48 +/- 33 vs. NB 95 +/- 30, and maternal Ig G4 10 +/- 8 vs. NB 4.9 +/- 2. The relation between the average levels of maternal and cord serum was 1, 1.5, 1.9 and 0.48 for Ig G1, Ig G2, Ig G3 and Ig G4, respectively. It was also proved a maximum decrease in the levels of the subclasses in the first three months for the Ig G3, a percentage being noticed in the third month, in relation to the NB level, of 18, 29, 1.9 and 19% for Ig G1, Ig G2, Ig G3 and Ig G4, respectively. After primovaccination, a response was produced and it affected the 4 subclasses: Ig G1 845 mg %, Ig G2 229 mg %, Ig G3 38 mg % and Ig G4 7.44 mg %, with an increment in relation to prevaccination values of 5.5, 3.7, 20.7 and 12.4, respectively. The authors concluded by showing reference patterns in the active placental transfer of Ig G subclasses in normal full-term newborns.